Fuel mixer



July 11, 1933. w DOBLE, JR 1,917,577

FUEL MIXER Filed Nov. 26, 1928 F 'IE1 E INVENTOR 'am A. flab/a JrPatented July 11, 1933 UNITED STATES WILLIAM A. DOIBLE, JR, OF BERKELEY,CALIFORNIA FUEL MIKE Application filed November 26, 1928. Serial No.321,890.

My invention relates to means for burning liquid fuels, such asdistillate, fuel oil and kerosene, and especially is concerned withmechanism for mixing the liquid fuel with a combustible proportionof'air. The efficiency of any means for consuming fuel oil or liquidfuels in general depends largely upon the thoroughness with which thefuel is intermixed with the air for combustion.

That is, the more homogeneous the fuel and air mixture, the better thecombustion and the greater the economy effected.

It is therefore one of the objects "of the present invention to insure averythoroughintermixture of the fuel and the air for combustion.

Another object of the invention is to provide means for breaking up anddisseminating a heavy fuel oil in an air stream, so that perfect.combustion of the heavy oil is obtained.

A further object of the invention is to pro vide means for convertingthe liquid fuel into a'fuel foam and regulating the rate of productionof the foam in proportion to the fuel demands of the burner. I

The foregoing and other objects are attained in the embodiment of theinvention shown in the drawing, in which Fig. 1 is a diagrammaticshowing of one modification of my invention.

Fig. 2 is a diagrammatic representation of another modification of myinvention.

Fig. 3 is a diagram showing an additional modification in accordancewith my invention.

In its preferred form, my invention includes a conduit thru which acurrent of air is induced to flow and into which a combustibleproportion of fuel foam is introduced.

In the modification disclosed in Fig. L'tliere is provided a conduit 6which terminates usually in a venturi 7 and thru which a current of airis induced to flow by a blower 8 preferably driven by an electric motor.The conduit 6 is adapted especially for use with furnaces or otherheaters, but the invention is applicable to other environments as well.For supplying a liquid fuel to'the current of air flowing thru theconduit, I preferably provide a fuel storage tank 9 and withdraw theliquid fuel through a pipe 11 and force it by means of a pump 12 into areservoir 13.

To regulate the height 'of fuel in the reser- 5 voir there is affordedan overflow tube 1i having a reverse bend16 therein acting as a fueltrap. The tube 14 terminates within the tank 9 and returns thereto anyfuel which overflows the upper end of the tube-14. To 6 accommodate thechanging fuel volume within the tank 9, an atmospheric vent 17' isprovided thereon.

From the reservoir 13, the withdrawn by a. pump into a pipe 19. leadingto a fuel foam pump 21. This fuel foam pump can be of any of therecognized kinds but preferably includes an eccentrically mounted rotor22- equipped with radially extending blades 23 which contact with thepump casing and afford a pumping action. The u .per portion of thereservoir 13 is suppli with air, as will later be described, and thisair is vwithdrawn by the V pump 21 through a pipe 24 provided with avalve 26 for regulating the flow therethrough. By regulating the actionof pump18. and by regulating valve 26, the relative proportions ofliquid fuel and of air which merge just prior to entering the foam pump21 are easily varied. The foam pump is effective not only to withdrawair and fuel from the reservoir 13, but is also e'fi'ective to churn orwhip the air and fuel together to provide a foam-like mixture. Sometimessuch a pump is termed a nebulizer.

From the foam pump the fuel foam is discharged through a tube 27 into acup 28 open liquid fuel is 18 and is introduced 65 at the top and havinga perforate bottom 29.

This cup is situated within a receiver 31 con veniently disposedadjacent the conduit 6. For inducing the flow of fuel foam from the cup28 into the conduit 6, I preferably afford a duct 32 extending 'nto theconduit 6 and communicating with t e interior of the receiver 31. Thecurrent of air flowing through the conduit 6 enters through duct 32 intothe receiver and affords an increased air pressure therein, whichassists the educ- 00 ing action of the stream of air passing through theconduit 6 to raise the fuel foam upward through a nozzle into theconduit 6. The air which is subsequently mixed with the liquid fuel toform a .foam is preferably drawn from the receiver 31 and the air c11-tering this receiver may be taken from the conduit 6 when an elevatedair pressure is desired, or it may be taken directly from theatmosphere.

An outlet for the fuel foam to the air conduit is provided through anozzle 33 leading from the interior of and encompassed by the cup 28into the throat of an auxiliary venturi 34 situated adjacentthe venturi7. The eduction of the venturi, with or without the additional pressureafforded by the air passing through duct 32, depending upon theoperating conditions, is ample to aspirate the fuel foam from the cup 28and mix it with the current of air flowing through the conduit 6 andthrough the venturi 7. The streamv of air passing through the conduit 6ordinarily does not possess suficient energy to raise and'disseminate aheavy fuel in liquid form, but by foaming the fuel, its weight per unitof volume is greatly decreased, so that it is readily lifted andaspirated by the .air stream.

To afford a return for any surplus fuel foam which is not aspirated andwhich passes through the perforate bottom 29 of the cup 28 or overflowsthe upper edge thereof, there is afforded a tube 36 extending into thereservoir 13. The surplus fuel foam collects in the reservoir 13, whenceit again passes through the foaming pump, preventing or minimizing theflow of air through the pump and thus reducing .the amount of foamproduced. The formation of the foam is thus automatically regulated, sothat a sufiicient or a slight excess of foam is continually produced,the amount of foam produced depending upon the fuel demands of theburner.

With the system described, there is introduced into a current of airfrom which a proportion has been by-passed, an amount of fuel foamwhich, when reintroduced into the main current 'of air, provides areadily combustible and thoroughly homogeneous mixnism for handling theliquid fuel.

ture'.

In Fig. 2, substantially the same scheme is disclosed with the exceptionof the mecha- Here, likewise, there is shown a conduit 6 having aventuri 7 through which a current of air is induced by a blower 8. Thefuel, however, is introduced through a pipe 39 into a reservoir 41.Communication between the pipe and the reservoir is controlled by avalve 42 operated by a float 43. dependent upon the level of liquid fuelwithin the reservoir, and

effective to maintain the level at approximately any predeterminedamount. From the reservoir the liquid is withdrawn by a pump 44 whichdischarges it into a pipe into a cup 51 situate in a receiver 52. The

receiver is in communication thru a duct 53 with the current of airpassingthru conduit 6 so that an added pressure is present within thereceiver. To accommodate the overflow from the cup 51 and also toprovide an amount of air within the reservoir 41, a tube 54 connects thereservoir with the receiver. Projecting into the cup 51 and terminatingwithin an auxiliary venturi 56'adjacent the ven turi 7, is anozzle 58.

This mechanism is effective to maintain a substantially constant levelof liquid fuel within the reservoir 41 and to provide a fuel foam whichwhen mixed with the current of air flowing in conduit 6 is readilycombustible, largely due to its homogeneity.

In Fig. 3 there is a similar arrangement in which a concluit6 having aventuri 7 thru which a current of air is induced by a blower 8 isprovided with a fuel foam supplying means. This consists of a reservoir61 supplied with fuel thru a pipe 62. A float 63 controlling a valve 64regulates the height of liquid fuel within the reservoir and keeps it atany predetermined level. The upper portion of the reservoir contains airwhich is educted thru a pipe 66 controlled by a valve 67 to a foam pump68. Within the pipe 66 is a constriction 69 into which projects a fuelnozzle 71 communicating with the liquid fuel within the reservoir 61 andcontrolled by a suitable valve 72. By proper manipulation of the valves67 and 72, the relative proportions of air and fuel entering the foaming.pump 68 are regulated. The foam pump discharges into a pipe 73 leadinginto a cup 74 situate within a receiver 76, so that fuel foamoverflowing from the cup can pass into the receiver 76 and thru a pipe77 into the reservoir 61.

To increase the pressure within the receiver, I provide a duct 78intersecting the conduit 6 and affording a passage for a proportion ofthe current of air flowing therethru into the receiver. Air may alsoflow thru the pipe 77 into the upper portion of the reservoir 61 fromwhich it can be withdrawn by the foam pump as described. Projecting intothe cup 74 and terminating in the throat of an auxiliary venturi 79 is afuel nozzle 81. I

This scheme like the two just described, is effective in introducinginto a current of air, a combustible proportion of a fuel foam which,when united with the remainder of the air current, is combustible.Furthermore, the result of all of the devices described is 'vironment inwhich it is desired to mix a liquid fuel with air in combustibleproportion.

It is to be understood that I do not limit myself to the form of thefuel burner shown and described herein, as the invention, as set forthin the following claims may be embodied in a plurality of forms.

I claim:

1. A fuel mixer including a conduit having a Venturi therein, means forcausing a current of air to fiow thru said conduit, a source of liquidfuel, a pump for mixing said fuel with air to form a fuel foam, acontainer to receive said fuel foam from said pump, and a ductconnecting said container and said conduit thru which said fuel foam isaspirated by said current of air.

2. A fuel mixer including a conduit, means for causing a current of airto flow through said conduit, a container open-to said conduit, meansfor whipping liquid fuel with air to form a fuel foam, means forsupplying said fuel foam to said container, and a fuel foam duct joiningsaid container to said conduit.

3. A fuel mixer including a conduit having a venturi therein, means forcausing a current of air to flow thru said conduit, a fuel foamcontainer, an air pipe joining said container to said conduit, a fuelfoam duct joining said container and said conduit, a cup in saidcontainer encompassing said duct, and means for supplying fuel foam tosaid cup.

4. A fuel mixer including a conduit having a venturi therein, means forcausing a current of air to flow thru said conduit, a fuel foamcontainer, an air pipe joining said container to said conduit, a fuelfoam duct joining said container to said conduit adjacent said venturi,a fuel and air tank, an air tube joining said container to said tank,and a fuel foam pump adapted to Withdraw fuel and air from said tank anddeliver fuel foam to said container.

5. A fuel mixer including a conduit, a container, means for producingand supplying fuel foam to said container, means for 3SP1-- rating fuelfoam from said container into said conduit, and means for regulating theamount of fuel foam produced in accordance with the amount of fuel foamaspirated. a

In testimony whereof, I have hereunto set my hand.

WILLIAM A. DOBLE, JR.

